In the border-collapse: collapse model, the width of a table must include half the table border according to CSS 2.1

1^st col. & row	2^nd col. thead	3^rd col.	4^th col.	5^th col.
2^nd row	thead	abcd	abcd	abcd
5^th row	tfoot	a	b	c
3^rd row	tbody	abc	abc	abc
4^th row	tbody	ab	ab	ab

The relevant CSS code in that page is
body {margin: 15px 100px;} #idTable {border-collapse: collapse; border: lime ridge 100px; width: 500px;} td {blue solid 4px;}

Reference: CSS 2.1 Section 17.6.2 Border-collapse model says:
"Note that in this model, the width of the table includes half the table border"

The table width should correspond to the row width as described in this W3C CSS 2.1, Section 17.6.2 image

Firefox 3, Seamonkey 2.x all pass this test. Firefox 2.0.0.13 and Konqueror 3.5.8 also pass this test but they return the wrong computed value for CSS width.